The present invention relates generally to cutting tools and more particularly to toolholders with clamping arrangements for clamping a replaceable cutting insert relative to the toolholder.
Replaceable and/or indexable cutting inserts are ordinarily secured to toolholders in recesses intended for the cutting inserts by clamp arrangements. The clamping arrangements are typically in the form of a screw or bolt that extends through a through hole in the cutting insert and mates with an internally threaded hole in the toolholder, or in the form of a clamping arm that contacts a surface of the insert to secure it to the toolholder.
A type of clamping arm is secured to a toolholder by a nut and bolt arrangement that connects the clamping arm to the toolholder body. Usually, an end of the clamping arm contacts the cutting insert, such as by extending into a recess in a top surface of the insert to prevent the insert from inadvertently becoming separated from the toolholder. In such an arrangement, to install a cutting insert, the nut and bolt must be loosened relative to each other sufficiently to permit the insert to be inserted under the end of the clamping arm that will secure the cutting insert to the tool holder. Until the nut and bolt are tightened sufficiently, the insert may fall out of the recess on the toolholder. This can be complicated by the possibility that the insert will have to be installed in an inconvenient location, making it necessary to hold the insert in place with one hand while the nut and bolt are tightened. Some cutting tools, such as those in WO2009022757 A1, JP2004058193A, and CN 101391311 A, provide spring loaded clamps wherein a spring is provided to urge the clamp away from a position in which the clamp secures an insert to a tool holder body. While such arrangements may facilitate to some degree removal of cutting inserts from toolholder bodies, they can complicate installation of cutting inserts. Ordinarily, removal of the insert requires loosening of a bolt securing a clamp to a toolholder body and the spring merely assists a user by raising the clamp as the bolt is loosened. WO2006133378 shows a tool-less quick change tool holder provided for cutting inserts.
It is desirable to provide a toolholder that facilitates installation of a cutting insert in a manner that minimizes the possibility of the insert falling off of the tool holder during installation. It is also desirable to provide a toolholder that facilitates quick removal and replacement of cutting inserts on toolholders.
According to an aspect of the present invention, a toolholder is provided for use with a cutting insert having a clamping opening. The toolholder comprises a tool holder body and a clamp pivotably mounted to and contacting the toolholder body and pivotable between a first position in which a protrusion of the clamp is disposed in a position in which it is received in the clamping opening in the cutting insert to secure the cutting insert to the toolholder body and a second position in which the protrusion is spaced, relative to the toolholder, upwardly from the first position so that the cutting insert is not secured to the toolholder body by the protrusion, wherein a resilient member urges the clamp to the first position and resists pivoting of the clamp to the second position. The toolholder comprises a lever arm attachable to the clamp for pivoting the clamp toward the second position against a resisting force of the resilient member.
According to another aspect of the invention, a method for changing cutting inserts on a toolholder is provided, the cutting inserts being of a type having a clamping opening, the toolholder comprising a toolholder body and a clamp pivotably mounted to the toolholder body, said tool holder comprising a lever arm attachable to the clamp for pivoting the clamp toward the second position against a resisting force of the resilient member comprising pivoting the clamp, against a force of a resilient member, from a first position relative to the tool holder body in which a protrusion of the clamp is disposed in the clamping opening in a first cutting insert to secure the first cutting insert to the toolholder body to a second position in which the protrusion is spaced, relative to the toolholder, upwardly from the first position so that the first cutting insert is not secured to the toolholder body by the protrusion removing the first cutting insert from the tool holder body positioning a second cutting insert on the toolholder body pivoting the clamp from the second position to the first position under the force of the resilient member to secure the second cutting insert to the toolholder body.